In a conventional factory or distribution warehouse, it is desirable to move loads along a transporting path that is predominately horizontal, but which may also involve travel uphill, downhill, diversion between subpaths, and the like. These systems provide an overhead conveyor system with rotating drive shafts, a carriage that is supported by the drive shaft or by a fixed support rail, and a carriage that has skewed drive wheels to engage with the rotating drive shaft. The engagement of the skewed wheels with the rotating drive shaft propels the carriage along the rotating drive shaft or along a fixed rail.
The present slip tube system relates to overhead conveyors of the type disclosed in U.S. Pat. No. 5,806,655 issued Sep. 15, 1998 to Tabler, in U.S. Pat. No. 5,785,168 issued Jul. 28, 1998 to Beall, Jr., in U.S. Pat. No. 4,203,511 issued May 20, 1980 to Uhing, in U.S. Pat. No. 3,164,104 issued Jan. 5, 1965 to Hunt, and in U.S. Pat. No. 3,850,280 issued Nov. 26, 1974 to Ohrnell. Shaft driven overhead conveyors have many advantages over the heavier load type conveyors such as the power and free conveyor; such advantages including quietness, cleanliness, less repair, easy diversion of load carrying carriages, buffering, speed variation along the conveying path, and generally greater flexibility in design.
Conventional prior art rotating shaft driven overhead conveyors can be constructed from a plurality of inline rotating drive shafts that move loads along the rotating drive shafts from the interaction of skewed or canted driven wheels attached to the carriage which engages with the rotating drive shaft. The canted driven wheels tractionally engage with the rotating drive shaft in a helical spiral path along an exterior drive surface of the rotating drive shaft to move the load along the overhead conveyor. A gap exists between the consecutive sections of the plurality of inline rotating drive shafts and a pillow block fits into this gap to support the ends of adjacent sections of the plurality of inline rotating drive shafts. With prior art systems, if the gap is too wide, the canted driven wheels decouple from the rotating drive shafts when moving across the gap, resulting in a drop of propulsive force to the carriage. With heavy loads, this loss of propulsive force can result in slowdown or stoppage of the carriage as the driven wheels decouple from the rotating drive shafts.
Consequently, a significant need exists for a drive system that can propel a load across the gaps between a plurality of rotating drive shafts, a bearing block of the drive system that can both support ends of two adjacent drive shafts and reduce the gap therebetween, a bearing block that can align with the conveying path, and a need for a carriage with drive rollers configured to be always in driven contact with at least one of the plurality of rotating drive shafts when passing across the gap between adjacent drive shafts.